The present invention relates to a clutch release bearing, and particularly a seal which is suitable for the clutch release bearing to achieve excellent seal performance.
The clutch is a power connecting and disconnecting device using a friction plate, and can be installed in a vehicle etc. such as automobiles, tractors, forklifts. For an input member of the clutch, a shift fork is used. In the case of operating the clutch, disconnection of power transmission is achieved by pressing in an axial direction the diaphragm spring in the clutch cover with the shift fork so as to release the energizing force of the diaphragm spring from the friction plate.
Incidentally, the shift fork is usually provided on the stationary side such as the vehicle body etc. The clutch cover is mounted to the flywheel etc. of the engine to rotate together with it. Accordingly, if the diaphragm spring of the clutch cover is directly pressed by the shift fork, the contact portions are subjected to wear.
Accordingly, as disclosed in Toku Kai Hei. No. 10-103380, a clutch release bearing device is provided between the diaphragm spring and the shift fork. The clutch release bearing device comprises a clutch release bearing having a rotatable ring which is abutted to the diaphragm spring and rotated together with it, and a stationary bearing support member which holds the bearing in a predetermined state while receiving an input from the shift fork.
Since the clutch is constructed such that a friction plate is interposed between the relatively rotating metal plates to utilize the friction forces acting each other for power transmission, abrasion powders are scattered from the friction plates on the clutch (engine) side. Then, such foreign matter enters between the races and the rolling members of the clutch release bearing, premature wear may be caused in the races and the rolling members. Accordingly, in the prior art clutch release device, a labyrinth seal is used between the inner ring and the outer ring for sealing, thereby preventing the penetration of the foreign matter.
Incidentally, recently, as the engine performance is increased, the heat generation from the engine is increased. In order to prevent the temperature increase around the engine due to the increased heat generation, forming air vents for cooling in the housing surrounding the clutch is considered. However, foreign matter such as dust and water etc. may enter through the air vents from outside. Although, the labyrinth seal can prevent relatively large solid foreign matter from entering the interior of the bearing, the foreign matter such as muddy water may pass through the labyrinth seal to enter between the races and the rolling members, thereby causing premature wear. As measures for such premature wear, the replacement of the clutch release bearing at a short cycle can be considered, but it will inconveniently increase the maintenance costs.
To solve the problems as mentioned above, an objective of the present invention is to provide a clutch release bearing with increased seal effects.
Another objective of the present invention is to provide a seal for clutch release bearing with increased seal effects.